Large scale equipment for the automatic processing of logs is well known in the forestry industry. Equipment such as waferizers, flakers, chippers and stranders are used to convert raw logs into wafers, flakes, chips and strands, respectively, for use in particle and strand boards and like products. An example of such large scale processing equipment is disclosed in applicant's U.S. Pat. No. 4,865,094 issued Sep. 12, 1989 for a Long Log Waferizer. Such large scale equipment is capable of processing large quantities of logs in a very short time. In order to keep this equipment fed with a steady supply of raw logs, a log feeding system that can handle large quantities of logs quickly and efficiently is required. It is important that the feeding system be capable of stacking and organizing logs into neat and compact batches for conversion by the processing equipment. If the logs are not organized correctly, jamming of the feeding system and the processing equipment is possible, leading to damage and wasted time while the machinery is being unjammed or repaired.
For example, when processing logs into flakes, it is important that the wood grain of the flake is parallel with the length of the flake, and therefore, the logs need to be aligned parallel with the cutting blades of the flaking equipment. Typically, the cutting blades are arranged to be parallel with the side walls of a feeding chute by which batches of logs are delivered to the flaker. The logs are fed into the chute at a loading region remote from the flaking equipment to lie aligned with the longitudinal axis of the chute. The logs are then moved longitudinally down the chute toward the flaking equipment to be processed. Most current log feeding system operate in two steps such that as one batch of logs is being loaded into the loading region, another batch of previously organized logs is being fed along the chute into the flaking equipment. As might be expected, when logs are fed into the loading area, there is the possibility that certain logs, particularly shorter logs, will lie diagonally across the chute. This reduces the quality of the flakes produced by the flaker as these misaligned logs are not parallel with the cutting blades. In addition, it is important that the logs are kept parallel between the chute walls as this allows the chute to be filled efficiently with the maximum amount of wood per unit volume of the chute. The flaker production capacity is reduced when misaligned logs are present, as the packing of the logs in the chute is also reduced.
In the past, the practice has been to keep the log feed chutes relatively narrow in an attempt to prevent log misalignment as the logs are delivered to the log loading region of the chute. A log length to chute width ratio of approximately 2:1 alleviates some misalignment problems.
There is still the desire to further increase log processing capacity and better align the logs for improved quality of the processed product. A number of systems have been developed that attempt to address the foregoing problems:
U.S. Pat. No. 5,070,918 discloses a feed device that uses a chute with fixed, parallel side walls to receive logs. Pivoting guides are extendable into the chute to exert limited control over settling of the logs, however, this design relies principally on a relatively narrow chute to control misalignment of logs.
U.S. Pat. No. 4,784,198 discloses a log loading apparatus that uses a V-shaped trough to store and release logs into a chipping chamber and relies on gravity and the sloped sides of the trough to organize the logs into compact batches. This arrangement requires an installation that has a great deal of overhead clearance to accommodate the V-shaped trough over the chipping chamber. The chipping chamber must be reinforced to withstand the impact of a batch of logs dropped all at once from above and there is no provision for correcting alignment of the logs once they have been dropped into the chipping chamber.
U.S. Pat. No. 3,638,792 includes a log feeding system that uses a log aligning device. The system uses a stationary wall and a sloped chain conveyor that includes a series of rolls formed with a spiral ridge. As the logs move up the chain conveyor, the spiral ridge engages the logs and moves them against the stationary wall which acts as a reference line for aligning logs. This system is intended exclusively for aligning logs and does not address the issue of compactly loading the logs into a delivery chute.